In meat grinder or food processor fitted with steel blade, grind together pork,
beef, pork fat and garlic. If using a food processor, be sure not to over
process. Remove and discard any gristle. Place meat in a large bowl.

Heat oil in a small saucepan over high heat. When it just starts to smoke, add
shrimp shells and heads and saute for 1 minute, stirring constantly, or until
bright pink in color.

Add shallots, garlic and anchos. Lower heat and cook,
stirring constantly, for about 4 minutes or until shallots, garlic, and anchos
are lightly toasted.

Add tomatoes, cilantro and serrano. Raise heat to medium and
cook 2 minutes. Add stock. Lower heat and simmer gently for 15 minutes. Do not
reduce. Pour into a blender and puree until smooth.

Mix masa harina with enough cold water to make a paste. Then,
with the motor running, add to the puree in the blender. Strain through a fine
sieve and stir in lime juice, honey and salt. Keep warm until ready to use.